6 Facts About NAC: The Powerful Glutathione Precursor Glutathione Precursors 120 vegetable capsules Jeff Clark, ND LLC Every time you exercise your body generates oxidative stress as a natural byproduct of muscle contraction and energy production. At moderate levels that is a healthy signal. But when exercise intensity exceeds Figure 1 from Thimerosal neurotoxicity is associated with glutathione depletion: protection with glutathione precursors. Semantic Scholar